From mid-2005, the PD's relations with the PNL also became strained. On 15 December 2007 the PD was merged into the new Democratic Liberal Party along with the Liberal Democratic Party (PLD), a splinter group from the PNL. The PLD approved the merger in a party congress with 933 in favour, six abstentions and one against.[11]

Later, in 2012, due to massive street protests, Prime Minister Emil Boc resigned and president Traian Basescu appointed the independent Mihai Razvan Ungureanu, former SIE commander, to form a new cabinet which was invested by a vote in Parliament in February 2012. After a two-months parliamentary protest, the opposition managed to pass a motion of no confidence on the 5th of May 2012, sending the PDL into opposition. When the government fell, Traian Basescu consulted the parliamentary parties and decided to nominate PSD leader Victor Ponta as Prime Minister.

On the 10th of June 2012, there were local elections. The PDL could win only two county council presidents (Arad and Alba) and 10 major city mayors (Cluj-Napoca, Brașov, Arad, Suceava, Drobeta-Turnu Severin, Alba Iulia, Tulcea, Târgu Mureș, Piatra Neamț, Târgoviște), which represented a crushing defeat, even if the party accqired 27% of Romania's mayors and almost 23% of the county and local councilors.

Because of these results, the president of PDL, Emil Boc, resigned and called for an early National Convention (congress) of the party, which was held on the 30th of June 2012. The Convention elected Vasile Blaga to become the new party president of PDL, and Gheorghe Flutur as secretary-general.

On 17 July 2014 it was announced that the new party formed from a future merger of the PDL and PNL would keep the National Liberal Party name, while being situated in the PDL's existing headquarters in Bucharest and would be registered by the end of 2014.[16] On 26 July 2014, a joint party congress of the PDL and PNL approved the merger.[17] On 28 July 2014 the PDL and PNL formed the Christian Liberal Alliance (ACL) to jointly contest the upcoming presidential election.[18][19] In the first round of the 2014 presidential election held on 2 November 2014, ACL candidate Klaus Iohannis received 30.4% of the vote, coming in second place behind Victor Ponta, the PSD candidate and incumbent Prime Minister.[20] In the runoff election held on 16 November 2014, Iohannis received 54.5% of the vote, becoming the surprise victor of the Romanian presidency.[21][22]